Generally, a steering column for a motor vehicle comprises a shaft, one of the ends of which is connected to a steering wheel which is actuated by the driver and the other end of which is connected to mechanical elements, such as a rotary transmission member or gear elements. The shaft of the steering column is mounted inside a housing by means of two rolling devices.
European patent application EP 1 956 254 A1 describes a pretensioned bearing which comprises an internal ring, an external ring which is provided with a casing in which two annular snap rings are mounted in order to form rolling paths, a row of balls which is arranged between the snap rings and the internal ring, and a pretensioning element which is produced from a resilient material and which is arranged axially between a first radial portion of the casing and one of the annular snap rings. A second annular portion of the casing is pressed against the other annular snap ring in order to apply an axial compression force to the pretensioning element and thus to preload the bearing radially and axially at the same time.
Conventionally, it is required that such steering column bearings operate with a rotation torque which is as small and as constant as possible. However, it may be desirable for an automotive application, in particular for top-of-the-range motor vehicles, to increase the resistant torque of the rotation of the steering column compared with mid-range vehicles. The driver then has to apply a greater torque to the steering wheel and thus has a sensation of the sturdiness of the vehicle. This driving sensation is very important since it contributes to the quality image, which a driver may have of a vehicle.
These are the constraints, which the invention is most specifically intended to overcome, by providing a new bearing device, which is simple and economical to produce and assemble whilst ensuring a high level of resistant torque.